**5. Conclusions**

Coatings with a thickness of 6–8 microns were obtained by magnetron sputtering of the TaSi2-Ta3B4-(Ta,Zr)B2 target in the Ar environment and gas mixtures Ar-N2 and Ar-C2H4. The coating deposited in argon had a pronounced columnar structure, while the transition to reactive sputtering suppressed the column growth. The main constituent of Ar-sputtered coatings was the h-TaSi2 phase with a crystallite size of ~10 nm. During the deposition in Ar-N2 and Ar-C2H4, a decrease in grain size, partial amorphization, and the formation of new phases based on TaN and TaC were observed. The coatings obtained at the maximum flow rate of N2 and C2H4 had high hardness at the level of 28–29 GPa and elastic recovery of 76%–78%. The transition to reactive deposition reduced the friction coefficient and the coatings' wear rate. All studied coatings resisted oxidation in the air up to 1000 ◦C owing to the formation of protective Ta-Si-O oxide films. Sputtering at optimal nitrogen and carbon concentrations modified the structure and increased the heat resistance and thermal cycling resistance of the coatings. The reactively-deposited coatings can briefly resist oxidation at 1200 ◦C.

The combination of high mechanical and tribological characteristics with high oxidation resistance makes the coatings in the Ta-Zr-Si-B-C-N system promising as protective coatings for various high-temperature applications, including high-performance dry machining tools and parts of heavily loaded friction units operating in aggressive environments, among others.

**Author Contributions:** Supervision, Deposition, Annealing, Investigation, Conceptualization, Writing & Editing: P.V.K.-K.; Tribo-Investigation, Profilometry, Analysis, Calculations, Writing: A.D.S.; Translation and Editing: S.A.V.; Investigation: V.V.K.; Formal Analysis: V.Y.L.; Project Administration, Resources: E.A.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research was funded by the Ministry of Science and Higher Education of the Russian Federation (Project No. 0718-2020-0034 of State assignment).

**Acknowledgments:** The authors are grateful to M.I. Petrzhik for the nanoindentation tests, N.V. Shvyndina for the SEM-EDS study, and P.A. Loginov for the XRD and HR TEM studies.

**Conflicts of Interest:** The authors declare no conflict of interest.
